Past research has established that listeners can accommodate a wide range of talkers in understanding language. How this adjustment operates, however, is a matter of debate. Here, listeners were exposed to spoken words from a speaker of an American English dialect in which the vowel /æ/ is raised before /g/, but not before /k/. Results from two experiments showed that listeners’ identification of /k/-final words like back (which are unaffected by the dialect) was facilitated by prior exposure to their dialect-affected /g/-final counterparts, e.g., bag. This facilitation occurred because the competition between interpretations, e.g., bag or back, while hearing the initial portion of the input [bæ], was mitigated by the reduced probability for the input to correspond to bag as produced by this talker. Thus, adaptation to an accent is not just a matter of adjusting the speech signal as it is being heard; adaptation involves dynamic adjustment of the representations stored in the lexicon, according to the characteristics of the speaker or the context.

In a study of optical cues to the visual perception of stress, three American English talkers spoke words that differed in lexical stress and sentences that differed in phrasal stress, while video and movements of the face were recorded. The production of stressed and unstressed syllables from these utterances was analyzed along many measures of facial movement, which were generally larger and faster in the stressed condition. In a visual perception experiment, 16 perceivers identified the location of stress in forced-choice judgments of video clips of these utterances (without audio). Phrasal stress was better perceived than lexical stress. The relation of the visual intelligibility of the prosody of these utterances to the optical characteristics of their production was analyzed to determine which cues are associated with successful visual perception. While most optical measures were correlated with perception performance, chin measures, especially Chin Opening Displacement, contributed the most to correct perception independently of the other measures. Thus, our results indicate that the information for visual stress perception is mainly associated with mouth opening movements.

The acoustic properties of foreigner-directed speech are surprisingly understudied, and many existing studies evoke imagined interlocutors to elicit foreigner-directed speech. This study provides an acoustic comparison of foreignerdirected and native-directed speech in real and imaginary conditions. Ten native U.S. English speakers described the path between landmarks on a map to two confederate listeners (one native English speaker and one native Mandarin speaker) and to two imagined listeners (described as a native U.S. English speaker and a non-native speaker). Vowel duration, rate of speech, and vowel space size were examined across native/foreigner and real/imagined conditions. Stressed vowels were longer, rate of speech was slower, and vowel space distances were expanded in the foreigner-directed and imaginary conditions than in the native-directed and real ones. Speakers made acoustic-phonetic adjustments in foreignerdirected speech that are consistent with those seen in listener-directed clear speech, and these additional adjustments were made for both native and foreign listeners when the listener was imagined rather than real.

Speech produced in the context of real or imagined communicative difficulties is characterized by hyperarticulation. Phonological neighborhood density (ND) conditions similar patterns in production: Words with many neighbors are hyperarticulated relative to words with fewer; Hi ND words also show greater coarticulation than Lo ND words [e.g., Scarborough, R. (2012). "Lexical similarity and speech production: Neighborhoods for nonwords," Lingua 122(2), 164-176]. Coarticulatory properties of "clear speech" are more variable across studies. This study examined hyperarticulation and nasal coarticulation across five real and simulated clear speech contexts and two neighborhood conditions, and investigated consequences of these details for word perception. The data revealed a continuum of (attempted) clarity, though real listener-directed speech (Real) differed from all of the simulated styles. Like the clearest simulated-context speech (spoken "as if to someone hard-of-hearing"-HOH), Real had greater hyperarticulation than other conditions. However, Real had the greatest coarticulatory nasality while HOH had the least. Lexical decisions were faster for words from Real than from HOH, indicating that speech produced in real communicative contexts (with hyperarticulation and increased coarticulation) was perceptually better than simulated clear speech. Hi ND words patterned with Real in production, and Real Hi ND words were clear enough to overcome the dense neighborhood disadvantage.

No abstract